The Journal of Neurophysiology Vol. 80 No. 6 December 1998, pp. 2870-2881
Copyright ©1998 The American Physiological Society

Intracortical Inhibition and Facilitation in Different Representations of the Human Motor Cortex

Robert Chen¹, Alda Tam¹, Cathrin Bütefisch¹, Brian Corwell¹, Ulf Ziemann¹, JOHN C. Rothwell², and Leonardo G. Cohen¹

¹ Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20982-1430; and ² Medical Research Council Human Movement and Balance Unit, The Institute of Neurology, London, United Kingdom

Chen, Robert, Alda Tam, Cathrin Bütefisch, Brian Corwell, Ulf Ziemann, John C. Rothwell, and Leonardo G. Cohen. Intracortical inhibition and facilitation in different representations of the human motor cortex. J. Neurophysiol. 80: 2870-2881, 1998. Intracortical inhibition (ICI) and intracortical facilitation (ICF) of the human motor cortex can be studied with paired transcranial magnetic stimulation (TMS). Plastic changes and some neurological disorders in humans are associated with changes in ICI and ICF. Although well characterized in the hand representation, it is not known if ICI and ICF vary across different body part representations. Therefore we studied ICI and ICF in different motor representations of the human motor cortex. The target muscles were rectus abdominus (RA), biceps brachii (BB), abductor pollicis brevis (APB), quadriceps femoris (QF), and abductor hallucis (AH). For each muscle, we measured the rest and active motor thresholds (MTs), the motor-evoked potential (MEP) stimulus-response curve (MEP recruitment), ICI, and ICF. The effects of different interstimulus intervals (ISIs) were studied with a conditioning stimulus (CS) intensity of 80% active MT. The effects of different CS intensities were studied at ISI of 2 ms for ICI and ISI of 15 ms for ICF. MT was lowest for APB, followed by BB, AH, and QF, and was highest for RA. Except for BB, MEP recruitment was generally steeper for muscles with lower MT. ICI and ICF were present in all the motor representations tested. The stimulus intensity necessary to elicit ICI was consistently lower than that required to elicit ICF, suggesting that they are mediated by separate mechanisms. Despite wide differences in MT and MEP recruitment, the absolute CS intensities (expressed as percentage of the stimulator's output) required to elicit ICI and ICF appear unrelated to MT and MEP recruitment in the different muscles tested. These findings suggest that the intracortical mechanisms for inhibition and facilitation in different motor representations are not related to the strength of corticospinal projections.

This article has been cited by other articles:

				W. J. Z\#8217;Graggen, A. B. Conforto, R. Wiest, L. Remonda, C. W. Hess, and A. Kaelin-Lang Mapping of direction and muscle representation in the human primary motor cortex controlling thumb movements J. Physiol., May 1, 2009; 587(9): 1977 - 1987. [Abstract] [Full Text] [PDF]

				F. Harraf, K. Ward, W. Man, G. Rafferty, K. Mills, M. Polkey, J. Moxham, and L. Kalra Transcranial magnetic stimulation study of expiratory muscle weakness in acute ischemic stroke Neurology, December 9, 2008; 71(24): 2000 - 2007. [Abstract] [Full Text] [PDF]

				S. Beck, S. P. Richardson, E. A. Shamim, N. Dang, M. Schubert, and M. Hallett Short Intracortical and Surround Inhibition Are Selectively Reduced during Movement Initiation in Focal Hand Dystonia J. Neurosci., October 8, 2008; 28(41): 10363 - 10369. [Abstract] [Full Text] [PDF]

				R. Gentner, K. Wankerl, C. Reinsberger, D. Zeller, and J. Classen Depression of Human Corticospinal Excitability Induced by Magnetic Theta-burst Stimulation: Evidence of Rapid Polarity-Reversing Metaplasticity Cereb Cortex, September 1, 2008; 18(9): 2046 - 2053. [Abstract] [Full Text] [PDF]

				E. Ortu, F. Deriu, A. Suppa, E. Giaconi, E. Tolu, and J. C. Rothwell Intracortical modulation of cortical-bulbar responses for the masseter muscle J. Physiol., July 15, 2008; 586(14): 3385 - 3404. [Abstract] [Full Text] [PDF]

				C. M. Butefisch, M. We ling, J. Netz, R. J. Seitz, and V. Homberg Relationship Between Interhemispheric Inhibition and Motor Cortex Excitability in Subacute Stroke Patients Neurorehabil Neural Repair, February 1, 2008; 22(1): 4 - 21. [Abstract] [PDF]

				J. Reis, O. B. Swayne, Y. Vandermeeren, M. Camus, M. A. Dimyan, M. Harris-Love, M. A. Perez, P. Ragert, J. C. Rothwell, and L. G. Cohen Contribution of transcranial magnetic stimulation to the understanding of cortical mechanisms involved in motor control J. Physiol., January 15, 2008; 586(2): 325 - 351. [Abstract] [Full Text] [PDF]

				M. A. Krutky and E. J. Perreault Motor Cortical Measures of Use-Dependent Plasticity Are Graded From Distal to Proximal in the Human Upper Limb J Neurophysiol, December 1, 2007; 98(6): 3230 - 3241. [Abstract] [Full Text] [PDF]

				Z. Ni, C. Gunraj, and R. Chen Short interval intracortical inhibition and facilitation during the silent period in human J. Physiol., September 15, 2007; 583(3): 971 - 982. [Abstract] [Full Text] [PDF]

				M. F. Del Olmo, B. Cheeran, G. Koch, and J. C. Rothwell Role of the Cerebellum in Externally Paced Rhythmic Finger Movements J Neurophysiol, July 1, 2007; 98(1): 145 - 152. [Abstract] [Full Text] [PDF]

				H. Lee, C. Gunraj, and R. Chen The effects of inhibitory and facilitatory intracortical circuits on interhemispheric inhibition in the human motor cortex J. Physiol., May 1, 2007; 580(3): 1021 - 1032. [Abstract] [Full Text] [PDF]

				M. L. Harris-Love, M. A. Perez, R. Chen, and L. G. Cohen Interhemispheric Inhibition in Distal and Proximal Arm Representations in the Primary Motor Cortex J Neurophysiol, March 1, 2007; 97(3): 2511 - 2515. [Abstract] [Full Text] [PDF]

				G. Koch, M. Franca, H. Mochizuki, B. Marconi, C. Caltagirone, and J. C. Rothwell Interactions between pairs of transcranial magnetic stimuli over the human left dorsal premotor cortex differ from those seen in primary motor cortex J. Physiol., January 15, 2007; 578(2): 551 - 562. [Abstract] [Full Text] [PDF]

				O. Soto, J. Valls-Sole, P. Shanahan, and J. Rothwell Reduction of Intracortical Inhibition in Soleus Muscle During Postural Activity J Neurophysiol, October 1, 2006; 96(4): 1711 - 1717. [Abstract] [Full Text] [PDF]

				G. O Paradiso, D. I Cunic, C. A Gunraj, and R. Chen Representation of facial muscles in human motor cortex J. Physiol., August 15, 2005; 567(1): 323 - 336. [Abstract] [Full Text] [PDF]

				V. Moliadze, D. Giannikopoulos, U. T Eysel, and K. Funke Paired-pulse transcranial magnetic stimulation protocol applied to visual cortex of anaesthetized cat: effects on visually evoked single-unit activity J. Physiol., August 1, 2005; 566(3): 955 - 965. [Abstract] [Full Text] [PDF]

				S. Kukaswadia, A. Wagle-Shukla, F. Morgante, C. Gunraj, and R. Chen Interactions between long latency afferent inhibition and interhemispheric inhibitions in the human motor cortex J. Physiol., March 15, 2005; 563(3): 915 - 924. [Abstract] [Full Text] [PDF]

				K. Matsunaga, A. Maruyama, T. Fujiwara, R. Nakanishi, S. Tsuji, and J. C. Rothwell Increased corticospinal excitability after 5 Hz rTMS over the human supplementary motor area J. Physiol., January 1, 2005; 562(1): 295 - 306. [Abstract] [Full Text] [PDF]

				T. Sharshar, N. S Hopkinson, S. Jonville, H. Prigent, R. Carlier, M. J Dayer, E. B Swallow, F. Lofaso, J. Moxham, and M. I Polkey Demonstration of a second rapidly conducting cortico-diaphragmatic pathway in humans J. Physiol., November 1, 2004; 560(3): 897 - 908. [Abstract] [Full Text] [PDF]

				A. Buccolieri, G. Abbruzzese, and J. C. Rothwell Relaxation from a voluntary contraction is preceded by increased excitability of motor cortical inhibitory circuits J. Physiol., July 15, 2004; 558(2): 685 - 695. [Abstract] [Full Text] [PDF]

				T. Sharshar, E. T. Ross, N. S. Hopkinson, R. Porcher, A. H. Nickol, S. Jonville, M. J. Dayer, N. Hart, J. Moxham, F. Lofaso, et al. Depression of diaphragm motor cortex excitability during mechanical ventilation J Appl Physiol, July 1, 2004; 97(1): 3 - 10. [Abstract] [Full Text] [PDF]

				C. M. Stinear and W. D. Byblow Impaired Modulation of Intracortical Inhibition in Focal Hand Dystonia Cereb Cortex, May 1, 2004; 14(5): 555 - 561. [Abstract] [Full Text] [PDF]

				M. Zoghi, S. L Pearce, and M. A Nordstrom Differential Modulation of Intracortical Inhibition in Human Motor Cortex during Selective Activation of an Intrinsic Hand Muscle J. Physiol., August 1, 2003; 550(3): 933 - 946. [Abstract] [Full Text] [PDF]

				M. Lotze, C. Braun, N. Birbaumer, S. Anders, and L. G. Cohen Motor learning elicited by voluntary drive Brain, April 1, 2003; 126(4): 866 - 872. [Abstract] [Full Text] [PDF]

				C. M. Stinear and W. D. Byblow Role of Intracortical Inhibition in Selective Hand Muscle Activation J Neurophysiol, April 1, 2003; 89(4): 2014 - 2020. [Abstract] [Full Text] [PDF]

				G. F. Wittenberg, R. Chen, K. Ishii, K. O. Bushara, E. Taub, L. H. Gerber, M. Hallett, and L. G. Cohen Constraint-Induced Therapy in Stroke: Magnetic-Stimulation Motor Maps and Cerebral Activation Neurorehabil Neural Repair, March 1, 2003; 17(1): 48 - 57. [Abstract] [PDF]

				C. M. Butefisch, J. Netz, M. Wessling, R. J. Seitz, and V. Homberg Remote changes in cortical excitability after stroke Brain, February 1, 2003; 126(2): 470 - 481. [Abstract] [Full Text] [PDF]

				A. Sailer, G. F Molnar, D. I Cunic, and R. Chen Effects of peripheral sensory input on cortical inhibition in humans J. Physiol., October 15, 2002; 544(2): 617 - 629. [Abstract] [Full Text] [PDF]

				Z. J Daskalakis, B. K Christensen, P. B Fitzgerald, L. Roshan, and R. Chen The mechanisms of interhemispheric inhibition in the human motor cortex J. Physiol., August 15, 2002; 543(1): 317 - 326. [Abstract] [Full Text] [PDF]

				H. Devanne, L. G. Cohen, N. Kouchtir-Devanne, and C. Capaday Integrated Motor Cortical Control of Task-Related Muscles During Pointing in Humans J Neurophysiol, June 1, 2002; 87(6): 3006 - 3017. [Abstract] [Full Text] [PDF]

				Z. J. Daskalakis, B. K. Christensen, R. Chen, P. B. Fitzgerald, R. B. Zipursky, and S. Kapur Evidence for Impaired Cortical Inhibition in Schizophrenia Using Transcranial Magnetic Stimulation Arch Gen Psychiatry, April 1, 2002; 59(4): 347 - 354. [Abstract] [Full Text] [PDF]

				F. Hummel, F. Andres, E. Altenmuller, J. Dichgans, and C. Gerloff Inhibitory control of acquired motor programmes in the human brain Brain, February 1, 2002; 125(2): 404 - 420. [Abstract] [Full Text] [PDF]

				L. Sawaki, B. Boroojerdi, A. Kaelin-Lang, A. H. Burstein, C. M. Butefisch, L. Kopylev, B. Davis, and L. G. Cohen Cholinergic Influences on Use-Dependent Plasticity J Neurophysiol, January 1, 2002; 87(1): 166 - 171. [Abstract] [Full Text] [PDF]

				S. C. Gandevia Spinal and Supraspinal Factors in Human Muscle Fatigue Physiol Rev, October 1, 2001; 81(4): 1725 - 1789. [Abstract] [Full Text] [PDF]

				J.-M. Aimonetti and J. B. Nielsen Changes in intracortical excitability induced by stimulation of wrist afferents in man J. Physiol., August 1, 2001; 534(3): 891 - 902. [Abstract] [Full Text] [PDF]

				T. D Sanger, R. R Garg, and R. Chen Interactions between two different inhibitory systems in the human motor cortex J. Physiol., January 15, 2001; 530(2): 307 - 317. [Abstract] [Full Text] [PDF]

				M Oliveri, C Caltagirone, M M Filippi, R Traversa, P Cicinelli, P Pasqualetti, and P M Rossini Paired transcranial magnetic stimulation protocols reveal a pattern of inhibition and facilitation in the human parietal cortex J. Physiol., December 1, 2000; 529(2): 461 - 468. [Abstract] [Full Text] [PDF]

				D. Burke, K. Bartley, I. J. Woodforth, A. Yakoubi, and J. P. H. Stephen The effects of a volatile anaesthetic on the excitability of human corticospinal axons Brain, May 1, 2000; 123(5): 992 - 1000. [Abstract] [Full Text] [PDF]

				R. Chen and R. Garg Facilitatory I Wave Interaction in Proximal Arm and Lower Limb Muscle Representations of the Human Motor Cortex J Neurophysiol, March 1, 2000; 83(3): 1426 - 1434. [Abstract] [Full Text] [PDF]